Implantable prosthetic devices have been used in numerous locations in the body. The most common use has been for restoring or improving upon normal body contour or augmenting as well as reconstruction of the female breast. The most common breast prosthesis is similar to that disclosed in U.S. Pat. No. 3,293,663 to Cronin, in which there is a flexible elastomeric container, typically silicone, which is filled with a soft gel, typically silicone gel or a saline solution or a combination of both.
A tissue expander is surgically implanted beneath tissue to be stretched and is filled at appropriate intervals with biocompatible fluid. After sufficient stretch has been achieved the tissue expander is removed and the newly available tissue used to cover a soft tissue defect or used to create a replacement body part. A breast tissue expander may be made convertible to a definitive, long-term, augmentative prosthesis, also known as an "implant".
As the field has progressed from simple wound coverage to reconstructing more realistic body parts incorporating prosthetic devices, especially in the case of the female breast, it has become evident that more control of the expansion process would be desirable in order to speed the process, to minimize the morbidity and the number of surgeries involved, as well as to refine the end result.
In breast reconstruction, major problems associated with the tissue expansion process include difficulty in creating a normal teardrop shaped and normally pendant breast due to the inability to create a properly shaped pocket. Presently the only options are either multiply chambered expanders with multiple injection ports or laminated component structures. These are commercially considered less than desirable because they are prohibitively expensive. They are functionally suboptimal as slippage at the soft tissue/expander interface may occur and there is a lack of purchase at the interface which is associated with inappropriate thinning and grossly non-uniform expansion of tissue.